Multi-cylinder axial piston hydraulic machines



Sept. 7, 1965 D. FIRTH ETAL 3,204,570

MULTI-CYLINDER AXIAL PISTON HYDRAULIC MACHINES Filed July 23, 1962 FIG].

United States Patent 3,204,570 MULTi- IYHNDER AXEAL PESTGN HYDRA UMC MAQHXNES Denald Firth and Roger Harvey Yorke Hancock, East Kilhri-de, Glasgow, Scotland, assignors to Council for Scientific and industrial Research, London, England, a corporation of the United Kingdnm Filed .iuly 23, 1962, Ser. No, 211,734- Claims priority, application Great Britain, Aug. 1, i961, 27,8'05/61 13 Claims. (Cl. ili3-l62) This invention relates to multi-cylinder axial piston hydraulic machines and has for an object to provide an improved construction of cylinder block which facilitates machining of the cylinder bores.

According to the present invention, a cylinder block assembly comprises an annular, one-piece block in which the cylinders are formed as through bores and a torque transmission port block which is integral with a drive shaft and has ports which register with the cylinders, the annular block and the port block being clamped together in fluid-tight relationship. The ports in the port block will register in known manner with inlet and outlet ports in a relatively stationary part of the machine in which the cylinder block assembly is used.

Preferably, the annular block is a snug fit on one or more locating lands on the drive shaft.

The annular block and the port block may be of different materials, thereby permitting the selection of the optimum material for the annular block, having regard to the requirements of the working of the pistons in the cylinder bores, and the optimum material for the port block having regard to the requirements of rigidity and wear in relation to the relatively stationary port plate or ported surface on the machine body.

For a detailed description of one construction of hy draulic machine to which the invention may be applied, reference may be made to the specification of application Serial No. 22,234 filed April 14, 1960, now Patent No. 3,099,429.

Freferred embodiments of the present invention will now be particularly described with reference to the accompanying drawings in which:

FIGURE 1 is a fragmentary axial cross section of a first embodiment,

FIGURE 2 is a scrap end view of FIGURE 1, and

FIGURE 3 is a fragmentary axial section of a modified embodiment.

Referring first to FIGURES 1 and 2, the drive shaft 1 of a swash plate type pump or motor has a spigot bearing 2 in an end block 3 of the machine. Adjacent the spigot 2 the shaft 1 has an integral flange or port block 4 and two spaced locating lands 5 over which is snugly fitted an annular cylinder block 6. The lands 5 merely serve to centre the block 6 and play no part in the transmission of torque between the shaft 1 and cylinder block 6.

The block 6 is a plain annulus with radial end faces, and is pierced through parallel to the axis of rotation with the requisite number of equi-angularly spaced plain cylinder bores 7. Since these open through both radial end faces of the block 6, machining and finishing of the bores 7 are simple operations. Within each cylinder 7 works a piston 8 having a slipper 9 bearing on the swash plate indicated by broken line it The flange 4 is of the same overall diameter as the cylinder block 6 and is pierced by ports 11 provided by through bores in the flange, these bores being of constant cross section of smaller diameter than the cylinders 7 and disposed on axes inclined from the annular block towards the shaft axis so as to register at their one ends with respective cylinders '7 and at their other ends with control ports dfihthiim Patented Sept. 7, 1965 12, 13 in a port plate M interposed between the flange or port block 4 and the end block 3 of the machine. The latter has inlet and outlet ports 15, 16 which register with the control ports 12, 13 in the port plate 14.. Each port 11 in the port block 4 opens at its end adjacent the annular block 6 into a shallow recess 17 coaxial with the respective cylinder 7 but of a diameter sufficiently greater than the cylinder to accommodate a sealing ring 18 adapted to be compressed between the floor of the recess 17 and the radial end wall of the annular block 6. Thus, when the interengaging surfaces of annular cylinder block 6 and the port block t are rigidly clamped together, they operate as a unitary cylinder block assembly both mechanica ly and hydraulically, the port block 4 providing the medium for torque transmission between the shaft l and the cylinder block assembly.

The port block 4 and annular cylinder block 6 may be rigidly clamped in any convenient manner, two preferred arrangements being illustrated in the drawings. In FIG- URES 1 and 2, clamping is shown as being effected by a ring of screws 19. These serve both to draw the components 4, 6 together tightly to form the hydraulic seal and to transmit torque between the two.

FIGURE 3 illustrates an alternative method of clamping the annular block 6 to the port block 4. In this modifiaction, the cylinder block has a shallow annular step 2th near its junction with port block t whilst the latter has a shoulder 21. A sleeve or ring 22 has internal complementary shoulders spaced apart so as to be a force fit over the step in and the shoulder 21, whilst the internal diameter of the sleeve or ring 22 is such that it must be shrunk into position over the step 2%) and shoulder 21. Dowels 23 are provided between the flange and annular block 6 to transmit torque between those two members. If desired, dowels may also be used in the construction shown in FIGURES .1 and 2.

By the two-part construction of the present invention it is possible to obtain the maximum rigidity from the integral shaft 1 and port block 4 formation whilst the material of the cylinder block 6 can be selected. to suit best the operating conditions of the pistons 8. Moreover, since both ends of the cylinder bores 7 and of the inclined ports 11 are accessible, machining and finishing of these components is rendered very simple, and hi h accuracy and good wear properties can be ensured.

We claim:

1. A cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block having angularly-spaced axial through bores therein constituting the cylinders, a drive shaft, a torque transmission flange made in one piece with the drive shaft and having through bores registering with the bores in the annular block, said bores in the flange being of smaller diameter than the bores in the annular block, and means clamping the annular block and the flange together.

2. A cylinder block assembly as claimed in claim 1, wherein the cylinder block is of material chosen to ail-0rd good piston and cylinder operation whilst the flange and drive shaft are of a different material chosen for rigidity and good wearing properties at the face of the flange remote from the cylinder block.

3. A cylinder block assembly according to claim 1 wherein said bores in the flange open adjacent the annular block into shallow recesses and sealing rings are provided in said recesses engaged between the floor thereof and the end wall of the annular block.

4. A cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block having a plurality of angularly-spaced axial through bores therein constituting the cylinders, a drive shaft fitting closely within the annular block, a torque transmission flange integral with the drive shaft and having through bores registering with the bores in the annular block, the bores in the flange being linear bores of constant cross section and of smaller diameter than the bores in the annular block and being inclined towards the axis of the shaft as they extend away from the annular block, and means clamping the annular block and the flange in sealing engagement.

5. A cylinder block assembly 'for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block having a plurality of angularly-spaced axial through bores constituting the cylinders, a drive shaft and a torque transmission flange thereon made in one piece, the flange having through bores which register at one end with the bores in the annular block and the flange and annular block having interengaging surfaces around the registering ends of the bores, and means clamping the interengaging surfaces together.

6. A cylinder block assembly according to claim 5 wherein the clamping means comprises screws carried by the annular block and engaging in the flange.

7. A cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block having a plurality of angularlyspaced axial through bores constituting the cylinders, a drive shaft and a torque transmission flange thereon made in one piece, the flange having through bores which register at one end with the bores in the annular block and the flange and annular block having interengaging surfaces around the registering ends of the bores, locating means maintaining registration of the bores in the flange and the bores in the block, and a clamp securing the flange to the annular block, said clamp comprising a shrunk-on ring embracing the flange and the annular block and having internal shoulders engaged over external shou ders on the flange and annular block.

8. A cylinder block assembly according to claim 7 wherein dowels are provided between the annular block and the flange.

9. A cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block in which all the cylinders are formed as angularly-spaced axially-extending through bores, a drive shaft fitting closely within the annular block, a torque transmission flange made in one piece with the drive shaft and having through bores registering with the bores in the annular block, and means clamping the flange against one axial end of the annular block, said shaft passing through the whole length of the annular block and projecting beyond the end of the block opposite to the end to which the flange is clamped and having a bearing portion extending from the flange away from the block.

10. A cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular, onepiece cylinder block in which all the cylinders are formed as angularly-spaced axially-extending through bores, a drive shaft carrying the annular block, which drive shaft extends through the annular block and projects axially from 'both ends thereof, a torque transmission flange made in one piece with the drive shaft and engaging one end of the annular block, said flange having ports therein registering with the bores in the annular block, and means clamping the annular block and the flange together and preventing relative rotation thereof.

11. in a multi-cylinder axial piston machine, an annular, one-piece cylinder block containing a plurality of cylinders formed as angularly-spaced axially-extending through bores, a drive shaft carrying the annular block, which drive shaft extends through the annular block and projects axially from both ends thereof, an end block in which said shaft is journalled, a torque transmission flange made in one piece with the drive shaft and engaging one end of the annular block, said flange having ports registering with the bores in the annular block, said flange having ports registering with the bores in the annular block and registrable with inlet and outlet ports in the end block, and means clamping the annular block and the flange together and preventing relative rotation thereof.

12. In a multi-cylinder axial piston machine, an end block having inlet and outlet ports, an annular, one-piece cylinder block containing a plurality of cylinders formed as angularly-spaced axially-extending through bores, a drive shaft, a torque transmission flange made in one piece with the drive shaft and disposed between the annular block and the end block, said flange having ports registering with the bores in the annular block and registrable with the ports in the end block, and means clamping the flange and the annular block together and preventing relative rotation thereof.

13. In a cylinder block assembly for a multi-cylinder axial piston hydraulic machine comprising an annular cylinder block in which all the cylinders are formed as angularly spaced axial through bores, a drive shaft on which said cylinder block is mounted, and a port block coupled to said shaft for rotation therewith, that improvement wherein the port block is constituted by a flange integral with the shaft and clamped to the end face of the cylinder block.

References Cited by the Examiner UNITED STATES PATENTS 1,019,521 3/12 Pratt l03-162 X 1,163,849 12/15 Pratt 103-162 X 1,506,892 9/24 Egersdorfer 103-162 1,539,616 5/25 Williams 103-162 1,840,864 1/32 Rayburn et a1 103162 2,733,666 2/56 Poulos 103162 2,844,104 7/58 Wennberg 103-462 3,092,036 6/63 Creighton 103162 FOREIGN PATENTS 968,595 3/58 Germany.

577,827 6/46 Great Britain.

849,634 9/60 Great Britain.

410,453 4/45 Italy.

248,917 3/48 Switzerland.

LAURENCE V. EFNER, Primary Examiner. 

1. A CYLINDER BLOCK ASSEMBLY FOR A MULTI-CYLINDER AXIAL PISTON HYDRAULIC MACHINE COMPRISING AN ANNULAR, ONEPIECE CYLINDER BLOCK HAVING ANGULARLY-SPACED AXIAL THROUGH BORES THEREIN CONSTITUTING THE CYLINDERS, A DRIVE SHAFT, A TORQUE TRANSMISSION FLANGE MADE IN ONE PIECE WITH THE DRIVE SHAFT AND HAVING THROUGH BORES REGISTERING WITH THE BORES IN THE ANNULAR BLOCK, SAID BORES IN THE FLANGE BEING OF SMALLER DIAMETER THAN THE BORES IN THE ANNULAR BLOCK, AND MEANS CLAMPING THE ANNULAR BLOCK AND THE FLANGE TOGETHER. 